1nbd_set_handshake_flags(3)          LIBNBD          nbd_set_handshake_flags(3)
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NAME

6       nbd_set_handshake_flags - control use of handshake flags
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SYNOPSIS

9        #include <libnbd.h>
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11        int nbd_set_handshake_flags (struct nbd_handle *h,
12                                     uint32_t flags);
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DESCRIPTION

15       By default, libnbd tries to negotiate all possible handshake flags that
16       are also supported by the server; since omitting a handshake flag can
17       prevent the use of other functionality such as TLS encryption or
18       structured replies.  However, for integration testing, it can be useful
19       to reduce the set of flags supported by the client to test that a
20       particular server can handle various clients that were compliant to
21       older versions of the NBD specification.
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23       The "flags" argument is a bitmask, including zero or more of the
24       following handshake flags:
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26       "LIBNBD_HANDSHAKE_FLAG_FIXED_NEWSTYLE" = 1
27           The server gracefully handles unknown option requests from the
28           client, rather than disconnecting.  Without this flag, a client
29           cannot safely request to use extensions such as TLS encryption or
30           structured replies, as the request may cause an older server to
31           drop the connection.
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33       "LIBNBD_HANDSHAKE_FLAG_NO_ZEROES" = 2
34           If the client is forced to use "NBD_OPT_EXPORT_NAME" instead of the
35           preferred "NBD_OPT_GO", this flag allows the server to send fewer
36           all-zero padding bytes over the connection.
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38       Future NBD extensions may add further flags.
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RETURN VALUE

41       If the call is successful the function returns 0.
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ERRORS

44       On error "-1" is returned.
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46       Refer to "ERROR HANDLING" in libnbd(3) for how to get further details
47       of the error.
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HANDLE STATE

50       The handle must be newly created, otherwise this call will return an
51       error.
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VERSION

54       This function first appeared in libnbd 1.2.
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56       If you need to test if this function is available at compile time check
57       if the following macro is defined:
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59        #define LIBNBD_HAVE_NBD_SET_HANDSHAKE_FLAGS 1
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SEE ALSO

62       nbd_create(3), nbd_get_handshake_flags(3),
63       nbd_set_request_structured_replies(3), libnbd(3).
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AUTHORS

66       Eric Blake
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68       Richard W.M. Jones
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71       Copyright (C) 2019 Red Hat Inc.
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LICENSE

74       This library is free software; you can redistribute it and/or modify it
75       under the terms of the GNU Lesser General Public License as published
76       by the Free Software Foundation; either version 2 of the License, or
77       (at your option) any later version.
78
79       This library is distributed in the hope that it will be useful, but
80       WITHOUT ANY WARRANTY; without even the implied warranty of
81       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
82       Lesser General Public License for more details.
83
84       You should have received a copy of the GNU Lesser General Public
85       License along with this library; if not, write to the Free Software
86       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
87       02110-1301 USA
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91libnbd-1.3.7                      2020-04-23        nbd_set_handshake_flags(3)
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